Handover Signaling in Wireless Networks

1. A method comprising: a) receiving, by a serving base station, a first radio resource control (RRC) message from a wireless device, said first RRC message comprising one or more parameters indicating whether said wireless device supports an enhanced physical downlink control channel (ePDCCH), said ePDCCH being a downlink channel configured to carry scheduling information for a plurality of downlink packets and a plurality of uplink packets; b) transmitting, by said serving base station, selectively and if said one or more parameters indicates support of said ePDCCH, at least one second RRC message configured to cause, in said wireless device, configuration of: i) first radio resources of a first ePDCCH of a first carrier, said first radio resources comprising one or more sets of resource blocks in a subset of subframes in a plurality of subframes, said at least one second RRC message indicating frequency resources for said first ePDCCH in terms of resource blocks in said subset of subframes; ii) second radio resources of a first data channel, said first radio resources and said second radio resources starting from the same OFDM symbol of each subframe in said subset of subframes; and iii) measurement parameters for measuring signal quality of at least one carrier of one or more target base stations; c) receiving, by said serving base station, at least one measurement report from said wireless device, said at least one measurement report comprising signal quality information of at least one of said at least one carrier of at least one of said one or more target base stations, said signal quality information derived at least in part employing measurements of at least one OFDM subcarrier; d) making a handover decision for said wireless device, by said serving base station, based at least in part on said at least one measurement report; and e) transmitting, by said serving base station and in response to said serving base station making said handover decision, at least one third message to at least one target base station, said at least one third message comprising at least one of: i) said one or more parameters indicating whether said wireless device supports said ePDCCH; and ii) configuration information of said first ePDCCH of said first carrier.

2. The method of claim 1 , before said at least one second RRC message is transmitted, further comprising: a) encrypting said at least one second RRC message; and b) protecting said at least one RRC second message by an integrity header.

3. The method of claim 1 , wherein said at least one second RRC message: a) further includes configuration information for physical channels for said wireless device; and b) is configured to cause said wireless device to set up or modify at least one radio bearer.

4. The method of claim 1 , wherein said at least one second RRC message further indicates a starting OFDM symbol of said first ePDCCH in said subset of subframes.

5. The method of claim 1 , wherein said at least one second RRC message further indicates a configuration of said subset of subframes in which said first radio resources of said first ePDCCH are configured.

6. The method of claim 1 , wherein said at least one second RRC message comprising: a) an identifier for said first carrier in a plurality of carriers, said plurality of carriers comprising: i) at least one backward compatible carrier; and ii) at least one non-backward compatible carrier; b) information identifying a carrier type for said first carrier, said carrier type being one of a backward compatible type and non-backward compatible type; and c) measurement parameters.

7. The method of claim 1 , wherein said first carrier is a non-backward compatible carrier.

8. The method of claim 1 , wherein said serving base station is configured to communicate employing: a) at least one non-backward compatible carrier; and b) at least one backward compatible carrier.

9. The method of claim 8 , wherein a first common reference signal overhead of each of said at least one non-backward compatible carrier is lower than a second common reference signal overhead of each of said at least one backward compatible carrier.

10. The method of claim 8 , further comprising said serving base station transmitting a channel state information reference signal on: a) said at least one non-backward compatible carrier; and b) said at least one backward compatible carrier.

11. The method of claim 1 , wherein one of said at least one second RRC message is configured to cause said wireless device to configure at least one of a physical layer parameter, a media access control layer parameter and a radio link control layer parameter.

12. A serving base station comprising: a) one or more communication interfaces; b) one or more processors; and c) memory storing instructions that, when executed, cause said serving base station to: i) receive a first radio resource control (RRC) message from a wireless device, said first RRC message comprising one or more parameters indicating whether said wireless device supports an enhanced physical downlink control channel (ePDCCH), said ePDCCH being a downlink channel configured to carry scheduling information for a plurality of downlink packets and a plurality of uplink packets; ii) transmit, selectively and if said one or more parameters indicates support of said ePDCCH, at least one second RRC message configured to cause, in said wireless device, configuration of: (1) first radio resources of a first ePDCCH of a first carrier, said first radio resources comprising one or more sets of resource blocks in a subset of subframes in a plurality of subframes, said at least one second RRC message indicating frequency resources for said first ePDCCH in terms of resource blocks in said subset of subframes; and (2) measurement parameters for measuring signal quality of at least one carrier of one or more target base stations; iii) receive at least one measurement report from said wireless device in response to said at least one second RRC message, said at least one measurement report comprising signal quality information of at least one of said at least one carrier of at least one of said one or more target base stations, said signal quality information derived at least in part employing measurements of at least one OFDM subcarrier; iv) make a handover decision for said wireless device, by said serving base station, based at least in part on said at least one measurement report; and; v) transmit, in response to said handover decision, at least one third message to at least one target base station, said at least one third message comprising at least one of: (1) said one or more parameters indicating whether said wireless device supports said ePDCCH; and (2) configuration information of said first ePDCCH of said first carrier.

13. The serving base station of claim 12 , wherein said serving base station is configured to communicate employing: a) at least one non-backward compatible carrier; and b) at least one backward compatible carrier.

14. The serving base station of claim 13 , wherein said instructions, when executed, further cause said serving base station to transmit a demodulation reference signal on: a) said at least one non-backward compatible carrier; and b) said at least one backward compatible carrier.

15. The serving base station of claim 12 , wherein one of said at least one second RRC message is configured to cause said wireless device to configure at least one of a physical layer parameter, a media access control layer parameter and a radio link control layer parameter.

16. The serving base station of claim 12 , wherein one of said at least one second RRC message comprises radio link configuration information comprising uplink channel configuration parameters and handover parameters.

17. A serving base station comprising: a) one or more communication interfaces; b) one or more processors; and c) memory storing instructions that, when executed, cause said serving base station to: i) receive a first radio resource control (RRC) message from a wireless device, said first RRC message comprising one or more parameters indicating whether said wireless device supports an enhanced physical downlink control channel (ePDCCH), said ePDCCH being a downlink channel configured to carry scheduling information for a plurality of downlink packets and a plurality of uplink packets; ii) transmit, selectively and if said one or more parameters indicates support of said ePDCCH, at least one second RRC message configured to cause, in said wireless device, configuration of first radio resources of a first ePDCCH of a first carrier, said first radio resources comprising one or more sets of resource blocks in a subset of subframes in a plurality of subframes, said at least one second RRC message indicating frequency resources for said first ePDCCH in terms of resource blocks in said subset of subframes; iii) make a handover decision for said wireless device; iv) transmit, in response to said handover decision, at least one third message to at least one target base station, said at least one third message comprising at least one of: (1) said one or more parameters indicating whether said wireless device supports said ePDCCH; and (2) configuration information of said first ePDCCH of said first carrier.

18. The serving base station of claim 17 , wherein one of said at least one second RRC message comprises radio resource configuration parameters comprising a physical channel configuration parameters.

19. The serving base station of claim 17 , wherein a format of said at least one measurement report is determined employing at least one of said at least one second RRC message.

20. The serving base station of claim 17 , wherein said at least one second RRC message further indicates a configuration of said subset of subframes in which said first radio resources of said first ePDCCH are configured.